    (Patent Article 1) International Patent Publication No. WO 9408943    (Patent Article 2) Japanese Patent Laid-Open Publication No. Hei 9-2579602    (Patent Article 3) International Patent Publication No. WO 0206268    (Patent Article 4) Japanese Patent Laid-Open Publication No. Hei 2002-53575    (Patent Article 5) Japanese Patent Laid-Open Publication No. Hei 2002-167382
Immunosuppressive agents are widely used as a treatment for autoimmune diseases such as rheumatoid arthritis, nephritis, osteoarthritis of and systemic lupus erythematosus, chronic inflammatory diseases such as inflammatory bowel disease, and allergic diseases such as asthma and dermatitis. Progress in medicine has led to the rise in the number of tissue and organ transplantations performed each year. In such a situation of modern medicine, having as much control as possible over the rejection following transplantation is a key to a successful transplantation. Immunosuppressive agents also play a significant role in this aspect.
In organ transplantations, antimetabolites, such as azathioprine and mycophenolate mofetil, calcineurin inhibitors, such as cyclosporin A and tacrolimus, and corticosteroid, such as prednisolone are typically used. However, some of these drugs are not effective enough while others require continuous monitoring of the blood drug level to avoid renal failure and other serious side effects. Thus, none of conventional immunosuppressive agents are satisfactory in view of efficacy and potential side effects.
Multiple drug combined-therapy, in which different immunosuppressive drugs with different mechanisms of action are used, is becoming increasingly common for the purposes of alleviating the side effects of the drugs and achieving sufficient immunosuppressive effects. Also, development of new types of immunosuppressive agents that have completely different mechanisms of action is sought.
In an effort to respond to such demands, the present inventors conducted a search for new types of immunosuppressive agents with main interest in 2-amino-1-ethanol derivatives.
While the use of 2-amino-1,3-propanediol derivatives as immunosuppressive agents has been described in Patent Articles No. 1 and No. 2, it has not been previously known that 2-amino-1-ethanol derivatives bearing a diaryl sulfide group or a diaryl ether group, the subject compounds of the present invention, exhibit significant immunosuppressive effects. Although Patent Articles No. 3, No. 4 and No. 5 disclose amino alcohol derivatives that act as immunosuppressive agents, these compounds have different structures from the compounds of the present invention.